# Safety stock

> Safety stock is the extra you hold to cover the weeks when sales run high or a delivery runs late.

- Source: https://storestandards.com/glossary/safety-stock/
- Updated: 2026-08-14
- Author: Priya Raghunathan, Founder, engineer, Store Standards

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Without it you plan for an average week, and an average week is not the one
that empties your shelf.

## A rough way to work it out

Take the busiest week of sales you have had for that line in the last year.
Take a typical week. The gap between them, multiplied by your
[lead time](https://storestandards.com/glossary/lead-time/) in weeks, is a sensible buffer.

Sell 20 a week normally, 35 in a good week, two-week lead time. The buffer is
30 units.

It is not exact. It is much better than a flat number applied to everything.

## Vary it by line

Hold more where being out hurts: your fast sellers, anything with a long lead
time, anything a customer would go elsewhere for rather than wait.

Hold less on slow lines. A buffer on something that sells one a month is
[dead stock](https://storestandards.com/glossary/dead-stock/) with a friendly name.

## Where it goes wrong

The buffer is set once and never revisited. Sales change, suppliers get
slower, and a number chosen two Christmases ago is still sitting there.

The other fault is treating safety stock as untouchable. It exists to be eaten
into during a bad week. A buffer you never dip into is not protection, it is
capital sitting still, and the [stockout](https://storestandards.com/glossary/stockout/) it was meant to
prevent never happens because the line was overstocked the whole time.

## Related terms

- [Reorder point](https://storestandards.com/glossary/reorder-point/): A reorder point is the stock level that tells you to order more, set so the delivery lands before you run out.
- [Lead time](https://storestandards.com/glossary/lead-time/): Lead time is how long it takes for stock to arrive after you place the order, measured from your side of the transaction.
- [Stockout](https://storestandards.com/glossary/stockout/): A stockout is running out of something a customer wanted to buy. The lost sale is usually the smallest part of the cost.